Stdout/stderr stall recovery code added.
Stdout/stderr stall recovery code added.

This stall situation can happen when program shares stdout with its child
e.g. command=bash -c "echo ahoj1; tail -f /dev/null"

zhangchunsheng/ramona,ateska/ramona,zhangchunsheng/ramona,ateska/ramona,ateska/ramona,zhangchunsheng/ramona